Radial fluid-film bearing

ABSTRACT

A hydrodynamic bearing for spindles and the like comprising a cylindrical shell surrounding the spindle. The shell is supported by three supports one of which is movable and is urged against the shell to deform it into triangular shape. The shell is housed in a sealed reservoir holding oil which provides a pressurized film between spindle and shaft tending to make the shell circular on rotation of the spindle.

United States Patent 1 Linda et a1. Feb. 20, 1973 [54] RADIAL FLUID-FILMBEARING [56] References Cited [75] Inventors: Josef Linda; BohuslavBelohoubek; UNITED STATES PATENTS 11 f P i sg a o rague 1,947,559 2/1934Mackensen ..308/73 3,009,748 11/1961 Pitner ..308/207 73 Assignee: TOSHostivar, Narodni Podnik, mmary Examine, Milton KaufmanPraha-l-lostivar, Czechoslovakia Assistant Examiner prank Susko IAtt0meyRichard Low and Murray Schaffer [22] Filed: March 15, 1971 v [57]ABSTRACT [21] Appl' 124267 A hydrodynamic bearing for spindles and thelike comprising a cylindrical shell surrounding the spindle. [30]Foreign Application Pri i y Data The shell is supported by threesupports one of which is movable and is urged against the shell todeform it March 17, 1970 Czechoslovakia ..175 4-70 into triangularshape. The shell is housed in a Sealed reservoir holding oil whichprovides a pressurized film [52] US. Cl ..308/122 between i d and shafttending to a the Shell [51] 1111. C1. ..Fl6c 17/02 circular on rotationof the Spindle -[58] Field of Search ..'..308/122, 73, 207

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JOSEP LHUDA B HusLA BPL L/OUBEK JMOSLAU MHRJHLEfi INVENTORS A TORNEIY)PATENTEU F5820 1973 Jose F L/N M @MUSLRV BE K RADIAL FLUID-FILM BEARINGBACKGROUND OF INVENTION The present invention relates to spindlebearings and in particular to hydrodynamic, radial fluid bearings forjournalling rotating shafts and the like.

Hydrodynamic bearings have been used for some time to journal rotatingspindle shafts. Such bearings permit relatively accurate location of thespindle, precise operation and rotation of the spindle, and aresufficiently rugged to absorb vibration impact and heavy work loading.These bearings fall into two groups: the first, wherein the radialclearance of the spindle is rigidly fixed notwithstanding its speed ofrotation; the second, wherein the radial clearance is automaticalyadjusted relative to the speed of spindle rotation. In both groups theentering wedge for initial fluid displacement is formed by co-action ofthe spindle with the journalling bearing shell; the provision of variouspivoting segmented elements; or by some manipulation of the bearingshell itself.

In bearings of the first group, the radial clearance is predeterminedaccording to a very precise and complex technological procedure basedupon such factors as the velocity of the spindle, rigidity defined as aratio of loading force to deformation, and heat generated, but primarilyupon the skill and experience of the technician. Once the clearance isset, it cannot be changed. For this reason such bearings are highlysusceptible to seizure and damage upon sudden changes in spindlerevolution. Adjustment, therefore, for the highest speed would notachieve optimum or even efficient operation at lower speeds, or viceversa.

In bearings of the second group while radial clearance has been achievedautomatically it is at the expense of very complex and complicatedmechanisms,

which have'required very high precision in their manufacture andassembly. The various component parts have had to be specially and verycarefully machined,

finished, polished, and assembled under the greatest care. In particularbearings of this second group have manufacturing tolerances in micronsand therefore are well beyond ordinary manufacturing standards.

It is the object of the present invention to provide hydrodynamicjournal bearing overcoming the prior art drawbacks and defects.

It is another object 'of the present invention to provide a hydrodynamicbearing which is automatically adjustable to provide the optimum radialclearance under all operating conditions and spindle speed.

It is a further object of the present invention to provide ahydrodynamic bearing which will perform optimally and efficiently indirect response to spindle speed notwithstanding variations therein.

It is another object of the present invention to provide an improvedradial fluid, journal bearing suitable for use in supporting spindle andshafts of machine tools and the like at the most optimum speeds.

It is a further object of this invention to provide a hydrodynamicjournal bearing with maximum rigidity, bearing capacity, and flexibilityof use.

It is a further object of this invention to provide a hydrodynamicjournal bearing having less heat and fricbearing.

It is a further object of the present invention to provide ahydrodynamic bearing having automatic response to changes in spindlespeed in a range from a vantages'will become apparent from the followingdisclosure.

SUMMARY OF THE INVENTION According to the present invention ahydrodynamic bearing for a rotating spindle or shaft is formed of acylindrical shell which surrounds the spindle. The shell is supported bya plurality of supports extending parallel to the axis of the shell andspaced about the circumference thereof. At least one of the supports ismounted for radial movement relative to the shell and is provided withbiasing means for urging it against the shell to deform it against theother supports. The shell is surrounded by a housing which forms areservoir for lubricating fluid. The rotation of the spindle displacesthe bearing fluid forming a pressurized film between the spindle andshell. The film is formed continuously around the spindle forcing theshell into cylindrical shape no matter at what speed the spindle isrotated.

Preferably the supports are symmetrically arranged and are three innumber, with two being fixed while one is normally biased by a spring.The housing comprises a rigid fixed wall or bore in a wall of a machinetool, and side retaining rings to which the supports are resilientlyattached.

Full details of the invention are given in the following description andin the appended drawings.

BRIEF DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 is a sectional view taken along line B-B of FIG. 2 showing thebearing of the present invention,

FIG. 2 is a sectional view along line A-A of FIG. 1,

FIG. 3 is a plan view of the bearing of FIGS. 1 and 2,

FIG. 4 is a side elevational view partially in section of alathe-grinder showing the application of the bearing of the presentinvention to the joumalling of a grinding spindle, and

FIG. 5 is a schematic view of the function of the bearing during (a)initial start-up, (b) non-work load operation, (0) loaded operation.

DESCRIPTION OF INVENTION For illustration the present invention will bedescribed in the form of a journal or radial bearing for thehorizontally rotating shaft of a machine tool such as a universallathe-grinder of conventional type although the application generally,to the support of rotating shafts will be obvious. Such machine is seenin FIG. 4 and in addition to the conventional lathe headstock A andtailstock B it comprises as housing body 1 set back rearwardly from theaxis thereof of the stocks. The housing body 1 rests upon a bed 21supported by the machine base and joumals' a shaft or spindle 2extending parallel to the axis of the headstock and tailstock. A

grinder wheel 25 is mounted at the forward end of the spindle 2 whilesuitable drive means 20, such as, fly wheels, gear box, pulley trainconnected to a motor, or a motor itself, is connected at the rear end.The specific details of such machine are believed to be so well knownthat further description here is not believed to be necessary.

The spindle 2 is mountedwithin the housing body 1 by means of a pair ofhydrodynamic radial journal bearings .23-formed in accordance with thepresent invention and located at the forward and rear ends. The spindle2 is preferably necked in one or more coaxial steps and is provided alsowith an axial or thrust hydrodynamic bearing 24 to prevent axialtranslation. A preferred form of axial bearing is fully describedin thecopending application of the same inventor based upon his Czechoslovakpatent application PV 2452-70 filed Apr.- 13, 1970.

Details of the radial journal bearing of the present invention is seenwith reference to FIGS. 1 3. The spindle 2 is set within a conformingco-axial bore 1a formed in the housing body. The bore 1a issubstantially larger in diameter than the spindle although, as will beseen, it forms the back of the hearing. The bore 1a of course, may beshaped along its axial length to conform to the differences in crosssection of the spindle 2 and may, if

desired, be lined with a liner or sleeve. The housing (and/or liner ifused) is preferably formed by material of high strength. A bearing shell3 having a diameter which is only slightly greater than the diameter ofthe spindle 2 is mounted about the spindle. The shell 3 may be providedwith a relatively smooth inner surface which forms a bearing surfacesurrounding the spindle, although it does not serve as a rotatingsurface in this invention. The shell 3 is further supported externally,at

three equidistant points from the wall of the housing bore 1a. The firstpoint'of support isalong the central vertical axis of the housing bore1a where the housing body 1, itself, is bored to provide a vertical hole16 directed radially toward the center of the bore 1a. A compressionspring 7, of preselected spring rate, is set within the hole 16 andbears at its lower end against a rest or stop member 6. The stop restmember 6 is generally in block form and has a cylindrical recess 17formed in its lower surface, which recess 17 is adapted to receive acylindrical prismatic body 5. The prismatic body has a lower surfacewhich is conformingly shaped to that of the outer surface of the shell3, and is provided 'with a central axial slot which causes the member 5to press against the shell along two axial lines to either side of theslot. Fitted within the slot is a bar 8. At a corresponding point, theshell 3 is provided with a corresponding slot into which the bar 8 isalso simultaneously inserted so that the shell 3 and prismatic member 5are keyed together. against relative rotation although radial movementis permitted. Since the prismatic member 5 fits within the recess ofrest member 6 they too are keyed together, thus preventing effectivehydrodynamic effect resulting from the present invention.

The prismatic member 5 is provided with pins 13 extending axiallyoutward of both its ends. The pins pass respectively through enlargedholes, formed in a pair of retaining rings 18 located on both sides ofthe prismatic member. The retaining rings 18 are annular ring members ofmetal or other high strength material having an inner diameter largerthan the shell 3 so as to surround the same and an outer diameter lessthan that of the bore in. The retaining rings 18 form the axial endstops of and support the bearing assembly as a whole. The

clearances between the rings 18 and the bore 10 and shell 3 arerespectively packed by an inner sealing ring 9 and an outer sealing ring10 set within the surfaces of their outer edges. The sealing rings 9 and10 are also annular and are preferably formed of rubber-like, plastic,or other suitable resilient sealing material and are adapted to abutresiliently against the outer surface of the shell and the inner wall ofbore la to seal the bearing. The prismatic member 5 isv itself sealedbetween the two end retaining rings 18 by an O-ring or similar sealingpacking 11 fit over the end pins 13. The end pins 13 are preferablyprovided with annular collars or grooves to retain the packing 11. Snapor C- clamps 15 or other fasteners of the clip-on or removable type areemployed at each end of the prismatic member 5 to retain it and its sealmembers in place.

The two remaining points at which the shell 3 is supported is offsetfrom the position of prismatic member 5 (i.e. the vertical axis) by toeither side. Located at each of these two points is a cylindrical roller4 arranged along an axis parallel to that of the spindle and along thelength of the shell. The diameter of each roller 4 is substantially thatof the radial distance between the outer surface of shell 3 and the wallof bore la. Each roller is provided at its ends with a pin 14 passingthrough and journalled in a corresponding hole formed in each of theannular retaining rings 18. The pins 14 of each of the rollers-4 arealso packed by an O- ring seals or similar means 12 and are alsoprovided with annular collars or grooves to seat the same in the mannerdescribed above with regard to the prismatic member 5. Snap fasteners 15are also used.

It will be observed that the retaining rings 18 provide a simple andeffective means for forming a hydrodynamically sealed bearing in aunitary compact assembly while still permitting the retaining rings,collars and support members to move. The snap rings 15 permit assemblyof the shell 3, the prismatic member 5 and rollers 4 into a portableeasily insertable and removable assemblage which can be mounted over thespindle 2 and in the bore 1a without completely tearing down themachine. To effect this, it will be understood that the rest member 6and the prismatic member 5 are only fit one with the other and areseparable; by removing the stop rest 6 the entire assembly is thusaxially movable in the bore la. Removal of the stop rest 6 can be easilymade by providing the housing body 1 with a longitudinal keyway in whicha corresponding key 30 (FIG. 4) may be fit. By withdrawing the key 30the spring 7 and the stop rest 6 may be removed. As seen in FIG. 4, thekey 30 may be vertically withdrawn although it may also be arranged tobe axially withdrawn from the keyway.

The arrangement of the retaining rings 18, seals 9 and 10 and packing 13and 14 enable the functioning of the device in another advantageousmanner. In operation the shell 3 is adapted to be deformed under bothstatic and dynamic loading. The deformation is permitted by the abilityof the rollers 4 to move about the outer surface of the shell 3 and thewall of the bore 1a within their resilient journals and by the resilientmounting of the prismatic member 5. The use of resilient sealing ringsand packings allow such deformation without distortion of the sideretaining rings 18 and simultaneously maintaining the integrity of thesealed reservoir and pressure within the bearing. Symmetrical.

deformation of the shell 3 is insured by this construction.

It will thus be seen that the present bearing assembly comprises a shell3 having a pair of rolling members 4 and a fixed member 5 spacedequidistant about it, and supported by side retaining rings 18, sealedwith respect to the mounting means. Thus formed the assembly is placedin the bore la resting on the rollers 4. The stressing memberscomprising rest 6 and spring 7 are inserted. The interior of the bearingthus forms an enclosed or sealed reservoir R which is then filled withsuitable lubricating oil of desired and predetermined viscosity. Thespindle is then inserted and the bearing assembly adjusted foroperation.

In the free or non-adjusted state the inner diameter is only somehundreths of a millimeter greater than that of the spindle 2. Adjustmentis necessary to delineate this radial clearance and to achieve optimumhydrodynamic function of the bearing. Static prestressing is thenapplied to the shell 3 to deform it and stress it also against thespindle 2 by the action of the spring 7 on the prismatic member 5. Thespring rate preselected for the effect desired biases the prismaticmember with a constant force. The adjustment causes the shell 3 todeform symmetrically and to lose its circular or cylindrical shape. Theshell assumes the shape of a somewhat symmetrical or equilateraltriangle and its inner walls bear against the spindle along threesurface lines relative to each of the points of contact between therollers 4 and the prismatic member 5 respectively, with the shell 3. Asa result wedge shape lubricating pockets 19 are formed. The shell 3 isformed outwardly directed with channels or grooves 19a of theconventional form for the passage of lubricating oil from thesurrounding reservoir to the wedge pockets 19. Upon such adjustment thespindle might 'be defined as being pre-stressed or preloaded by a staticforce P as seen in FIG. 5 (a) acting radially inward against the spindle2 at each point of contact.

In the initial stage of machine operation the spindle 2 is caused torotate without any external loading (i.e. no grinding). The lubricatingoil molecules located in the wedges 19 are displaced and form acontinuous film of oil about the spindle 2. As seen in FIG. 5 (b) thefilm has a uniform thickness of 8,, about the spindle. The hydrodynamicforces generated in the moving wedges 19 generates an increasingpressure of the oil between the shell 3 and the spindle 2 forcing theshell 3 outwardly into a more circular cross sectional shape.

The geometrical conditions (i.e..the deformation of a cylinder into atriangular cross section) generate an increase in pressure in the oilfilm and a change in behavior of the shell 3 (FIG. 5). This occurs as aconsequence of the fact that the upper support, Le:

prismatic member 5 is pushed against the pre-stressing spring 7. Theamount of this push, in the vertical direction is three times thethickness of the oil film (i.e.: 3 8 Consequently, the direct verticalmovement of the spindle 2 is twice the thickness of the film of oil(i.e.: 2 8 as seen in FIG. 5 (b). Thus the spindle 2 flows on by 2 8,,and is completely surrounded by pressurized oil. Meanwhile the staticloading or prestressing force P, continues to act. As a final result themagnitude of the hydrodynamic forces in the initial start up stage shownin FIG. 5 (b) and without external loading can be defined by the formulawhere C is the constant of spring and C is the resilient back pressureon the prismatic member 5.

To enable a better understanding of the conditions within the bearingthe actual load of the oil may be thought of as being divided into aninner load P and an outer load P The inner load, prior to the actualwork loaded operation of the spindle is caused by the force required todeform the shell 3 and pre-stress spring 7 when the oil film 6,, iscreated and further by the static pre-stressing P, Thus, when thespindle 2 is placed into initial rotation the inner force P directlyequals the hydrodynamic force P and the spindle assumes a balancedposition concentric about the center 0.

The outer loading is a function of the masses of the spindle, grindingwheel and driving members and in the course of operation is constantlybeing changed as a result of the forces acting upon its members bygrinding or cutting. Thus, the bearing reacts under operation to theimpression of the outer load P which of course, is a directionalresultant of all the forces. The axis of the spindle is displaced by avalue e into a new balanced position O offset from the center 0 of theshell 3, as seen in FIG. 5 (c). The thickness of the initial oil film isalso changed and assumes a non-uniform characteristic about the spindlein conformity to the resultant external load P The upper supportprismatic member 5 is also displaced by a value z. The pressure forcesgenerated at each of the supporting points 4 and 5 are also changed andassume non-uniform values P P and P respectively. These forces must beinbalance with the inner load P as well as the reaction to the outer loadP This state of balance is expressed by the following formulas:

6 B P =P =P (C +C)Z where [3 equals the angle between resultantdirection of force P and the diameter passing through the movablesupport P,.

The above equations mathematically describe the conduct of the forceswithin the bearing. They are basic to the mathematical theory requiredto determine the required rigidity and corresponding parameters of theshell 3 in order to obtain the optimum function, bearing capacity andprecision.

During operation, as seen in FIG. 5 (c) the bearing reaches a state ofbalanced dynamic forces. When rotation of the spindle occurs the oilpressure of course, increases and deforming the shell into a more nearlyperfect cylinder. As a consequence of the relationship noted above allthe parts automatically adjust into dynamic balance providing a film ofoil completely around the spindle, eliminating throughout the entireoperation any contact between the spindle and the shell. The center Onwith an optimum clearance is thus determined for the best performance.The optimum rigidity of the bearing and its optimum load capacity areobtained in this manner with-out any danger of hearing damage orseizure. As the speed of the spindle increases (i.e. is R.P.M.'sincrease) the hydrodynamic forces in the lubricating oil increasescorrespondingly. The pressure of the lubricating oil increases and sodisplaces the spindle away from the walls of the shell with greaterpressure. This pressure remains responsive to the actual exteriorloading and the spindle is constantly and automatically adjusted about acenter of balance even under changing speeds. The fact that the spindleis constantly floating and moving on a surrounding fllm of oil has theadvantageous result of preventing seizure. Thus, the spindle can operateat a great range of speeds, optimumly, efficiently andwithout damage.The range of speed (i.e. R.P.M.) can be varied in a range where thehighest speed can be 25 or more times as great as the minimum efficientspeed (that is the speeds can be easily adjusted for any givenbearingspindle arrangement in a range of 1:25 R.P.M.

Since the actual mechanical load on the shell 3 is minimal, the shell 3may be chosen of a suitable bearing material such as steel, brass etc.The thin film of oil which always separates the spindle and the shellreduces frictional forces to almost nil and therefore, permits the shellto be made of inexpensive materials if desired. The shell wall thicknessis not critical and can be chosen only to meet the mechanical stress andloading required. It is necessary that it be thick enough to withstandthe oil pressure but thin enough to be deformed by the roller supportsand the oil under operating conditions described above.

It will thus be seen that a hydrodynamic bearing, or

radial film bearing journal of improved performance and reliability hasbeen achieved. The bearing does not require adjustment when externalload conditions are changed since such adjustment isautomatic. Thebearing may thus also be made inexpensively and simply. Unlike prior artbearings which were required to be manufactured with the utmostprecision the present hearing may be made with gross tolerances andrelatively rough dimensions. The fact that there are no rotatingcontacting surfaces and the fact the the bearing itself is a pressurizedfilm of oil permits the surfaces and dimensions of the metallic parts tobe only roughly gauged. Automatic adjustment is effected even under suchconditions.

The present disclosure illustrates the invention. It will be appreciatedthat various modifications and changes are possible and such will beobvious to those skilled in this art. Limitation of the presentinvention is ,therefore not to be made except relative tothe appendedclaims.

What is claimed 1. A hydrodynamic bearing comprising a rotating spindleor the like, a cylindrical shell surrounding said spindle, a pluralityof support means extending parallel to the axis of said shell and spacedabout the circumference thereof, at least one of said support meansbeing mounted for radial movement relative to said shell, biasing meansfor urging said movable support means against said shell to temporarilydeform said shell, housing means surrounding said shell and supportmeans for forming a sealed reservoir, and a bearing fluid located insaid reservoir, channel means-within said shell for passing said bearingfluid from said reservoir to the space about said spindle, the rotationof said spindle causing said bearing fluid to form a pressurized filmbetween said spindle and shell tending to expand said shell against saidmovable support and into its normally cylindrical shape. I

2. The bearing according to claim 1 wherein said support means aresymmetrically arranged-about said shell.

3. The bearing according to claim 1 having their support means locatedequidistant about the circumference of the shell, two of said supportmeans being fixed against radial movement between said shell and thewalls of said bore, the third support being movably biased by springmeans urging said third support against said shell to temporarily deformthe same into a triangular shape.

4. The bearing according to claim 3 including means for preventingrotation of said shell relative to the housmg.

5. The bearing according to claim 4 wherein said housing is formed witha radial hole, aligned with said movable support, and includes a springlocated in saidhole and a rest member interposed between said spring andsaid movable support, said rest member and said movable support and saidshell having corresponding slots and a key inserted therein to preventrotation of said shell but permit radial movement.

6. The apparatus according to claim 3v wherein said fixed supportscomprise cylindrical rollers.

7. The bearing according to claim 3 wherein said housing means includinga pair of annular retaining rings surrounding said shell and journallingsaid support means and resilient seals interposed between said rings andthe surface of said shell and the wall of the bore in said housing toseal the same and permit radial movement of said rings relative to saidbore.

8. The bearing according to claim 7 wherein said support means areprovided with axially extending pins journalled with opening formedwithin said retaining rings, said opening providing radial clearanceabout said pins, and includes resilient packing means sealing saidclearance and permitting radial movement of said pins within saidopening.

9. The bearing according to claim 7 including channel means fordelivering fluid from said reservoir to the interface between said shelland spindle.

10. A fluid bearing system journalling a rotatable shaft, comprising adeformable journal sleeve surrounding said shaft, support means forsupporting said sleeve about its outer circumference along three axiallines at least one of said support means being freely movable radiallyof said sleeve, means resiliently prestressing said one support means todeform said shell to create at least one wedge with respect to saidshaft and supplying fluid to said wedge whereby on rotation of saidshaft said wedge displaces said fluid and causes the same to create apressurized film layer continuously about the shaft, to cause saidsleeve to overcome said prestressing. j

11. The system according to claim 10 wherein when said one support isprestressed under no external load condition on said shaft the value ofthe hydrodynamic force on said shell at any support point is calculatedaccording to the formula:

where C is the rate constant of the prestressing means, C is the rate ofback pressure against said prestressing means, 8 is the thickness of thefluid film and P is the pressure extended by said one support radiallyon said shell.

12. The system according to claim 11 wherein when a load is applied tosaid shaft the hydrodynamic force on the shell at any supporting pointcan be calculated according to the following formulas:

2. P COS P911COS P COS(60 and Y z is the deviation between the originalposition of said prestressed member and its position during rotation.

l i t

1. A hydrodynamic bearing comprising a rotating spindle or the like, acylindrical shell surrounding said spindle, a plurality of support meansextending parallel to the axis of said shell and spaced about thecircumference thereof, at least one of said support means being mountedfor radial movement relative to said shell, biasing means for urgingsaid movable support means against said shell to temporarily deform saidshell, housing means surrounding said shell and support means forforming a sealed reservoir, and a bearing fluid located in saidreservoir, channel means within said shell for passing said bearingfluid from said reservoir to the space about said spindle, the rotationof said spindle causing said bearing fluid to form a pressurized filmbetween said spindle and shell tending to expand said shell against saidmovable support and into its normally cylindrical shape.
 1. Ahydrodynamic bearing comprising a rotating spindle or the like, acylindrical shell surrounding said spindle, a plurality of support meansextending parallel to the axis of said shell and spaced about thecircumference thereof, at least one of said support means being mountedfor radial movement relative to said shell, biasing means for urgingsaid movable support means against said shell to temporarily deform saidshell, housing means surrounding said shell and support means forforming a sealed reservoir, and a bearing fluid located in saidreservoir, channel means within said shell for passing said bearingfluid from said reservoir to the space about said spindle, the rotationof said spindle causing said bearing fluid to form a pressurized filmbetween said spindle and shell tending to expand said shell against saidmovable support and into its normally cylindrical shape.
 2. The bearingaccording to claim 1 wherein said support means are symmetricallyarranged about said shell.
 3. The bearing according to claim 1 havingtheir support means located equidistant about the circumference of theshell, two of said support means being fixed against radial movementbetween said shell and the walls of said bore, the third support beingmovably biased by spring means urging said third support against saidshell to temporarily deform the same into a triangular shape.
 4. Thebearing according to claim 3 including means for preventing rotation ofsaid shell relative to the housing.
 5. The bearing according to claim 4wherein said housing is formed with a radial hole, aligned with saidmovable support, and includes a spring located in said hole and a restmember interposed between said spring and said movable support, saidrest member and said movable support and said shell having correspondingslots and a key inserted therein to prevent rotation of said shell butpermit radial movement.
 6. The apparatus according to claim 3 whereinsaid fixed supports comprise cylindrical rollers.
 7. The bearingaccording to claim 3 wherein said housing means including a pair ofannular retaining rings surrounding said shell and journalling saidsupport means and resilient seals interposed between said rings and thesurface of said shell and the wall of the bore in said housing to sealthe same and permit radial movement of said rings relative to said bore.8. The bearing according to claim 7 wherein said support means areprovided with axially extending pins journalled with opening formedwithin said retaining rings, said opening providing radial clearanceabout said pins, and includes resilient packing means sealing saidclearance and permitting radial movement of said pins within saidopening.
 9. The bearing according to claim 7 including channel means fordelivering fluid from said reservoir to the interface between said shelland spindle.
 10. A fluid bearing system journalling a rotatable shaft,comprising a deformable journal sleeve surrounding said shaft, supportmeans for supporting said sleeve about its outer circumference alongthree axial lines at least one of said support means being freelymovable radially of said sleeve, means resiliently prestressing said onesupport means to deform said shell to create at least one wedge withrespect to said shaft and supplying fluid to said wedge whereby onrOtation of said shaft said wedge displaces said fluid and causes thesame to create a pressurized film layer continuously about the shaft, tocause said sleeve to overcome said prestressing.
 11. The systemaccording to claim 10 wherein when said one support is prestressed underno external load condition on said shaft the value of the hydrodynamicforce on said shell at any support point is calculated according to theformula:
 1. PDO (CB+C) 3 delta O + PS where C is the rate constant ofthe prestressing means, CB is the rate of back pressure against saidprestressing means, delta O is the thickness of the fluid film and PS isthe pressure extended by said one support radially on said shell.